photo of Timothy J. Hoellein

Timothy J. Hoellein

Assistant Professor Biology and Environmental Science


Phone: office (646) 660-6247:
lab (646) 660-6245

Fax: (646)660-6201

Originally from western Pennsylvania, I graduated with a B.S. in biology, magna cum laude, from West Virginia Wesleyan College in May 2000, with a minor in chemistry and completion of the Honors Program.  After graduation, I  spent a couple of years employed in different biology fields.  I worked with dolphins for 2 years with Dolphins Plus in Key Largo, Florida and British Virgin Islands.   I spent a season working on a US Geological Survey research project on disease ecology of prairie dogs and black footed ferrets in central Montana.  

Drawing upon my formative years spent in the Lake Erie and Pittsburgh regions of Pennsylvania, and through my job experience in the Florida Keys and Caribbean, I ultimately decided to pursue my Ph.D. in aquatic ecology at the University of Notre Dame.   I  felt this would be the best way to develop my interests and talents in advocacy for the understanding, education, and conservation of freshwater ecosystems.  


My research has focused on the effects of  1) restoration strategies and 2) seasonal change on ecosystem processes in aquatic ecosystems.  Both of these factors have the potential to alter rates of nutrient cycling, metabolism, microbial communities, organic matter dynamics, and fish communities via changes in light, leaf litter inputs, temperature, and stream substratum types.  However, few studies have considered the interaction between seasonal dynamics and restoration projects in their evaluations.


General Biology 1003: Baruch College

Undergraduate Teaching Assistant:  Principles of Biology, Diversity and Function,  Experimental Biology

Graduate Teaching Assistant: Aquatic Ecology

Teaching Apprentice: General Ecology

Guest Lecturer: Aquatic Ecology, General Ecology, Human Impacts and the Environment, Stream Ecology, and Stream Ecology: Methods, Loyola University of Chicago and University of Notre Dame

Certification of Teaching Excellence in Biological Sciences.  University of Notre Dame 10/15/06  


  • Hoellein, T.J., J.L. Tank, E.J. Rosi-Marshall, and S.A. Entrekin. In press.  Temporal variation in substratum-specific rates of N uptake and metabolism and their relative contribution at the reach scale.  Journal of the North American Benthological Society
  • Kominoski, J.S., T.J. Hoellein, J.J. Kelly, and C. M. Pringle. In press. Does mixing litter of different qualities alter stream microbial diversity and functioning on individual litter species? Oikos.
  • Entrekin, S.A., J.L. Tank, E.J. Rosi-Marshall, T.J. Hoellein, and G.A. Lamberti. 2008. Responses in organic matter accumulation and processing to an experimental wood addition in three headwater streams. Freshwater Biology 53:1642–1657.
  • Hoellein, T.J., J.L. Tank, E.J. Rosi-Marshall, S.A. Entrekin, and G.A. Lamberti. 2007. Controls on spatial and temporal variation of nutrient uptake in three Michigan headwater streams.  Limnology and Oceanography 52 (5) 1964-1977.  Hoellein et al. 2007.pdf
  • Entrekin, S.A., E.J. Rosi-Marshall, J.L. Tank, T.J. Hoellein, and G.A. Lamberti. 2007. Macroinvertebrate secondary production in forested sand-bottom streams of the Upper Midwest.  Journal of the North American Benthological Society. 26 (3): 472-490. Entrekin et al. 2007.pdf


As a new professor at Baruch College, my career vision is to combine environmental research with teaching and public service.  My overarching goal is to influence public  awareness and restoration of local  freshwater ecosystems through research, education, and outreach.  I am also keenly interested in collaborating with other instructors, researchers, and generally interested citizens to include ecological perspectives in subjects such as ethics, law, economics, and social justice.

Curriculum vitae

The City University of New York